Prime Minister Julia Gillard said her "very loving thoughts" were with the dead soldier's family and comrades "at this time of great stress and distress for them."

"What is clear is we have lost a brave soldier who was going about difficult and dangerous work in Afghanistan," she said.

"His loss will be mourned by the whole nation."

Ms Gillard said Australian forces remained committed to the timetable which will see them hand over responsibility to Afghan forces in 2014.

But she said "predictions" were that "there will still be active fighting needed against the insurgency" after the handover and said "there will be a continuing role for Special Forces until transition is complete."

"Having just been in Afghanistan, I can say that our troops there are in good spirits. Their morale remains high even though during the course of this year they have seen a great deal of loss," she continued.

"They are very determined to see the mission that we have set ourselves through, a mission with a defined strategy and a defined end point."

Defence Minister Stephen Smith confirmed the dead soldier was 24 years old, and expressed his condolences.

"The Government very strongly continues to believe that completing our transition mission in Afghanistan is in Australia's national interest," he said.

"When the operation has completed, then more details of this matter can also be provided."

Opposition Leader Tony Abbott said the Coalition's thoughts and prayers were with the soldier's family and friends.